JPH0431463A - Electrical circuit material - Google Patents

Abstract

PURPOSE:To obtain the title material in which metallic particles are uniformly dispersed in a high concentration and which can give a high-elaboration high- reliability circuit board which excels in conductivity characteristics, etc., even when the content of the metallic particles is small, by selecting the title material in which specified metallic particles are dispersed in an organic binder. CONSTITUTION:The title material wherein fine metallic particles obtained by reacting an organic metal salt (e.g. silver trifluoroacetate) with a reducing agent for said organic metal salt [e.g. 2,2-methylenebis(4-ethyl-6-t-butylphenol)] in the presence of an organic binder (e.g. polyvinyl butyral) are dispersed in said organic binder is selected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric circuit material in which fine metal particles are suitably dispersed in a binder by carrying out a reaction between an organic metal salt and a reducing agent in an organic binder. . This electric circuit material can be used not only as a circuit material that simply ensures continuity, but also as an electric circuit with various functions such as a resistive element, a heating circuit, a magnetic circuit, etc., depending on the type, composition, and dispersion state of the metal fine particles. be.

[Conventional technology]

With the development of the electronic industry, various functional materials are required, and in particular, many composite materials having various electrical properties are being used. For example, in electronic devices equipped with a large number of ICs and LSIs, electric circuit patterns are often used to combine, control, and integrate each element. These various electric circuits require higher precision and higher performance materials as electronic devices become smaller and lighter.

For this purpose, various conductive paints have already been used in printing methods, and methods have been proposed in which copper foil is patterned by etching, and circuit boards are formed by electroless plating and electroplating. However, with conventional techniques, high-definition patterns cannot necessarily be produced in large quantities with good reproducibility, and there is a need for better, higher-quality materials.

[Problems to be Solved by the Invention] The present invention provides a method in which fine metal particles are present in a highly concentrated and uniformly dispersed state, and good conductive and electrical properties can be obtained with as little metal fine particles as possible, resulting in high definition and reliability. The aim is to create a high-quality circuit board. For this purpose, it is necessary to control the particle size and shape of the metal fine particles, as well as the formation of a secondary structure in which the metal fine particles aggregate.

[Means to solve the problem]

The present invention originated from the discovery of a new phenomenon already discovered by the present inventors, and led to the invention of a useful electric circuit material. The materials forming the basic concept of this invention are described in, for example, Japanese Patent Laid-Open No. 2-74389.

That is, in the second aspect of the present invention, the binder is already present when the metal fine particles are formed by a reduction reaction so that the metal fine particles are suitably dispersed in the binder as an electric circuit material. Moreover, as a catalyst for the reaction to obtain these metal fine particles, a metal nobler than the organic metal salt to be reduced can be contained as a catalyst nucleus.

The present invention is an electric circuit material in which fine metal particles obtained by reacting an organic metal salt and a reducing agent for the organic metal salt in the presence of an organic binder are dispersed in the organic binder, and in particular, This composite material relates to an electric circuit material comprising metal fine particles and an organic binder formed in the presence of a metal catalyst nucleus nobler than the organic metal salt in a redox reaction between the organic metal salt and the reducing agent.

As the organometallic salt used in the present invention, two
- Metal salts such as M, silver, palladium, chromium, cobalt, and lead, and chelate compounds thereof are used. Particularly representative metal salts include metal salts of carboxylic acids such as hehenic acid, stearic acid, oleic acid, and acetic acid; metal salts of nitrogen-containing compounds such as phthalazinone and benzotriazole; chelate compounds of acetylacetone and ethylenediaminetetraacetic acid; Examples include metal salts of diazosulfonate and metal salts of sulfinic acid. Metal salts that are particularly soluble in organic binders are useful in the present invention, examples of which include metal salts of fluorine-containing carboxylic acids and fluorine-containing chelate compounds.

The reducing agent used in the present invention is one that reduces metal salts.For metal salts that are easily reduced, a weak reducing agent such as hindered phenol is sufficient, but for metal salts that are difficult to reduce, hydrazines and ascorbin A strong reducing agent such as an acid is chosen.

In the present invention, in particular, when a trace amount of a metal species bluer than the metal species of the organic metal salt is contained as catalyst nuclei, fine metal particles to be reduced can be formed at desired positions in the organic binder. For example, when an organic metal salt and a reducing agent are contained in an organic binder and this is stretched into a thin film, a very small amount of a metal species nobler than the metal species of the organic metal salt is attached to the surface as catalyst nuclei. By accelerating the reaction on the surface, reduced metal particles can be intensively formed on the surface of the stretched material. As described above, in the present invention, it is extremely effective to contain a very small amount of a metal species nobler than the metal species of the organic metal salt as a catalyst core in providing a thin film-like high-performance electric circuit material. In the present invention, a metal catalyst nucleus more noble than an organic metal salt refers to a metal catalyst nucleus whose presence promotes the reaction between an organic metal salt and a reducing agent. For example, when the organic metal salt is an organic silver salt, nobler metal catalyst nuclei include gold, palladium, platinum, rhodium, mercury, thallium, lead, etc.
Metallic silver itself can also serve as a metal catalyst nucleus. This metal catalyst core may be a compound such as a metal sulfide or oxide.

Methods for forming these metal catalyst nuclei include the application of an electroless plating pretreatment method in which palladium nuclei are formed by sequentially immersing them in an aqueous solution of palladium chloride and aqueous solution of stannous chloride, or the application of a trace amount of metal by vapor deposition, sputtering, etc. A suitable method is selected from among various methods, such as a method of attachment, a method of treatment with a reducing gas such as hydrogen or hydrogen sulfide, and a method of pretreatment with actinic rays, X-rays, gamma rays, etc.

In addition, as a method for forming a metal catalyst nucleus, a small amount of the organic metal salt is reduced in advance using a metal more important than the organic metal salt of the present invention or a reducing agent for the organic metal salt, and the metal nucleus thus formed is converted into a metal catalyst nucleus. It can also be used as

In the present invention, a method can be adopted in which a pattern of an electric circuit material is formed by utilizing the photosensitivity of an organic metal salt or by adding a photosensitive compound such as silver halide. In this method, an organic metal salt and a reducing agent are coated with an organic binder in advance, dried, and then a sheet with catalyst nuclei attached to the surface is prepared, and an electrical circuit plate is obtained by exposing the sheet to light through a mask pattern and heating it. It is something.

In the exposed part, a large number of catalyst nuclei are formed inside the material due to exposure, so that the redox reaction is accelerated inside the material.

On the other hand, in the exposed portion of the valve, fine metal particles are present at a high concentration near the surface due to catalyst nuclei attached to the surface. This is the first time that it has been found that the electrical properties of the exposed and non-exposed areas are different. For example, in the non-exposed area, metal fine particles are present at a high concentration and are partially aggregated, so they are conductive, whereas in the exposed area, the metal fine particles are loosely dispersed inside, so they are non-conductive. Such a remarkable difference in electrical properties was discovered for the first time in the present invention, and it was also found that a high-definition pattern could be obtained. Moreover, such a difference in conductivity can be made more noticeable by electroplating or the like.

In the present invention, nickel, copper, silver, palladium, etc. are generally used as organic metal salts to obtain a conductive pattern, and cobalt,
Alternatively, metal salts such as cobalt and platinum are used.

In addition, tungsten, nickel, chromium, etc. are used as the material for circuitizing the heating element.

In the present invention, patterning is usually carried out by exposure in this way, but scanning with various laser beams, electron beam irradiation, X-ray irradiation, etc. can also be carried out in addition to ordinary ultraviolet light and visible light.

Although it does not match the purpose of high definition, as a simple and inexpensive process, the organic metal salt of the present invention and the reducing agent are reacted in advance in a suitable binder-soluble solvent, so that the metal fine particles are dissolved in the binder. The formed coating liquid may be prepared, and a pattern may be printed using a gravure coater, a screen printer, or the like. The metal fine particles may be reacted at room temperature, or if the reaction is slow, the metal particles may be reacted at room temperature.
It may be heated to about 50°C. Note that patterning by this printing method can also be applied to a solution before the reaction between the organic metal salt of the present invention and the reducing agent starts.

The organic binder used in the present invention is not particularly limited as long as it is solvent soluble, but hydrophobic binders are preferred, such as polystyrene, polymethyl methacrylate, polyvinyl butyral, linear polyester resin,
It can be selected from linear polyurethane resins and the like. The ratio of the metal fine particles to the organic binder of the present invention is preferably in the range of 100:1 to 1:10 by weight.

In particular, in order to exhibit suitable performance as an electric circuit material, it is preferable that the content of metal fine particles be as high as possible, but on the other hand, if the content is too large, it becomes difficult to coat the material into a smooth sheet.

The size of metal fine particles is greatly influenced by the type of metal salt, heating temperature, type of reducing agent, presence or absence of a solvent, presence or absence of a metal catalyst nucleus that is more noble than the organic metal salt, and conversely, the desired size can be obtained by controlling these conditions. It is possible to obtain fine metal particles with a size and shape of . Generally, the size of metal fine particles is controlled to be about 5 nm to 50 μm as primary particles, and a secondary agglomerated structure is observed.

The electrical circuit material of the present invention can be used on various inorganic material substrates such as glass, alumina, and mica, on polyester films,
It is used by forming a pattern on an organic polymer material substrate such as a polyimide film or epoxy substrate. moreover,
The electrical circuit materials of the present invention include polyester, polyacrylate, polymethacrylate, polyimide, polyurethane,
It may be protected by coating or laminating with various resins such as epoxy resin.

In addition to being used in the form of a sheet, the material of the present invention may be used in the form of a sheet processed by heat pressing or the like, or it may be impregnated into a nonwoven fabric or the like.

Although the material of the present invention was invented as an electric circuit material, it can also be applied to various products applying patterning technology using photosensitivity, decoration, printing fields, etc.

Examples are described below to explain the present invention in more detail, but the present invention is not limited thereto.

Example 1 A solution consisting of the following component (I) was prepared.

Component (I) Silver trifluoroacetate 200 g Polyvinyl butyral 30 g 2.2-methicine bis(
2-butanone 1000 g toluene 200 g This solution was homogenized by stirring for approximately 1 hour, and passed through a filter with an average diameter of 0.3 μ to remove undissolved substances and dirt. After that, it was uniformly coated onto a polyethylene terephthalate film having a thickness of 80 μm so that the coating thickness after drying was 13 μm, and then dried.

This film was passed through each treatment tank containing the following aqueous solutions (1) and (2) for 30 seconds and dried again.

Aqueous solution (1) Palladium chloride 500■ Concentrated hydrochloric acid
20-distilled water 1000 all Aqueous solution (2) Stannous chloride 500 ■ Concentrated hydrochloric acid
20ml distilled water 1000ml The operations up to this step were performed in a dark room.

Next, mask pattern (positive type) on the obtained film
for 1 minute with a 500W ultra-high pressure mercury lamp.
It was exposed to light from a distance of cm. Furthermore, this film 1
When heated at 50° C. for 3 minutes, a reflective silver luster pattern was formed in the unexposed areas, while a blackened silver metal dispersion layer was formed inside the sensitive material layer in the exposed areas. It was confirmed by a simple test using a tester that the silver glossy pattern part was conductive and the blackened part was non-conductive.

This test uses a resolution test pattern with 20 images/
It was confirmed that it was possible to form a thin wire of m.

Example 2 Using the silver metal pattern obtained in Example 1 as an electrode, a copper metal layer with a thickness of about 10 μm was formed on the conductive pattern by electroplating. At this time, the blackened silver portion remained non-conductive and no change was observed in appearance. This sheet was laminated with a polyester film of about 30 μm and could be used as a flexible wiring material.

Example 3 In component (1) of Example 1, nickel phenylsulfonate was used instead of silver-gold salt reduction, heptane was used as a solvent, polyisobutylene was used as a binder, and N-methyl-P-amino-phenol sulfate was used as a reducing agent ( 1)
It was used in the same ratio.

The second solution was applied and dried in the same manner as in Example 1, then treated with aqueous solutions (1) and (2), pattern exposed, and then heated at 140''C for 5 minutes to obtain a conductive pattern. This metallic nickel-based material was found to be useful as an electric circuit material, as in Example 1.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (2)

[Claims] (1) Electric circuit material in which fine metal particles obtained by reacting an organic metal salt and a reducing agent for the organic metal salt in the presence of an organic binder are dispersed in the organic binder. (2) The electric circuit material according to claim (1) comprises metal fine particles formed in the redox reaction between an organic metal salt and a reducing agent in the presence of a metal catalyst nucleus nobler than the organic metal salt and an organic binder. Electric circuit material (3) Claim (1) or (
2) A sheet-shaped electrical circuit board in which the electrical circuit material forms a minute electrical circuit.